An aluminum water battery-fuel cell hybrid power system for autonomous underwater vehicles

Abstract

The application discloses an aluminum water cell-fuel cell hybrid power system for an autonomous underwater vehicle, and particularly relates to the field of the vehicle. Hydrogen is generated through an aluminum water reactor, seawater oxygen extraction and oxygen supply subsystems provide oxygen, the oxygen is input into a fuel cell stack to generate electric energy, the hydrogen is provided through the aluminum water reactor, the safety risk and the structural complexity problem existing in the high-pressure hydrogen storage scheme are solved, the oxygen is provided through the seawater oxygen extraction and oxygen supply subsystems, and the problems existing in the oxygen storage scheme are avoided; the electrolyte heat of the aluminum water reactor and the tail gas heat of the fuel cell stack are recycled and utilized through a waste heat recovery and heat management subsystem; byproducts generated by the aluminum water reactor are recycled through a byproduct treatment and water circulation subsystem, wastewater generated by the fuel cell stack is purified and recycled, and the above-mentioned subsystems are controlled in combination with an energy management and safety control subsystem, so that water management imbalance is avoided.

Description

Technical Field

[0001] This invention relates to the field of aircraft, and more particularly to an aluminum-water battery-fuel cell hybrid power system for autonomous underwater vehicles. Background Technology

[0002] Autonomous underwater vehicles (AUVs) are widely used in marine surveys, resource exploration, underwater reconnaissance, seabed equipment inspection, and special operations. Their endurance, stealth, and reliability are highly dependent on the performance of their energy systems. Current AUV power systems primarily use lithium-ion batteries, single fuel cells, or, to a lesser extent, a combination of auxiliary energy storage and fuel cells. While lithium-ion batteries are technologically mature and easy to control, their limited energy density makes it difficult to simultaneously meet the demands of long endurance, long range, and high peak power for AUVs. While single hydrogen fuel cells offer high power generation efficiency and good output quality, they suffer from the following drawbacks in underwater applications: traditional high-pressure hydrogen storage solutions pose safety risks, have complex system structures, and underwater platforms place high demands on the arrangement, sealing, and pressure resistance of high-pressure gas storage equipment; underwater environments cannot directly rely on air for oxygen supply, and using a complete oxygen storage solution would increase system weight, volume, and complexity; under conditions of low temperature, high pressure, and low dissolved oxygen in the deep sea, fuel cell stacks are prone to problems such as insufficient reactant gas supply, decreased reaction temperature, and water management imbalance; most existing fuel cell systems do not efficiently recover waste heat from exhaust gases, resulting in poor low-temperature start-up capability and low overall energy utilization efficiency. Summary of the Invention

[0003] The main objective of this application is to provide an aluminum-water battery-fuel cell hybrid power system for autonomous underwater vehicles, which aims to solve the problems of insufficient reactant gas supply, reaction temperature drop, and water management imbalance in existing hydrogen fuel cells of vehicles.

[0004] To achieve the above objectives, this application provides an aluminum-water battery-fuel cell hybrid power system for autonomous underwater vehicles, including an aluminum-water reaction hydrogen production subsystem, a hydrogen pressure regulation and supply unit, a seawater oxygenation and supply subsystem, a fuel cell power generation system, a waste heat recovery and thermal management subsystem, a product processing and water circulation subsystem, and an energy management and safety control subsystem. The aluminum-water reaction hydrogen production subsystem includes an aluminum-water reactor. The fuel inlet of the aluminum-water reactor is connected to an aluminum fuel tank, and the reactant outlet is sequentially connected to a gas-liquid separator, a hydrogen purifier, and a buffer hydrogen storage tank. The liquid outlet of the gas-liquid separator is sequentially connected to a circulating electrolyte tank, a circulating pump, and a filter. The filter is connected to the liquid inlet of the aluminum-water reactor. The hydrogen pressure regulating and supply unit is connected to a buffer hydrogen storage tank for regulating the pressure of the output hydrogen. The seawater oxygenation and supply subsystem includes a seawater oxygen supply branch and a secondary oxygen supply branch; The fuel cell power generation system includes a fuel cell stack. The anode of the fuel cell stack is connected to a hydrogen pressure regulation and supply unit, the cathode is connected to a seawater oxygenation and oxygen supply switching subsystem, and the output end is connected in sequence to a power conversion module, a power conversion and distribution unit, and an auxiliary energy storage unit. The waste heat recovery and thermal management subsystem is connected to the aluminum water reactor and the fuel cell stack, respectively, to recover and utilize the heat generated by the electrolyte and the exhaust gas of the fuel cell stack. The product processing and water circulation subsystem is connected to the aluminum water reactor and the fuel cell stack, respectively, and is used to recover the by-products generated by the aluminum water reactor and to purify and recover the wastewater generated by the fuel cell stack. The energy management and safety control subsystem is connected to the aluminum water reactor, hydrogen pressure regulation and supply unit, seawater oxygenation and supply subsystem, fuel cell stack, waste heat recovery and thermal management subsystem, and product processing and water circulation subsystem, respectively. It is used to determine the predicted power demand and issue control commands to the aluminum water reactor, hydrogen pressure regulation and supply unit, seawater oxygenation and supply subsystem, fuel cell stack, waste heat recovery and thermal management subsystem, or product processing and water circulation subsystem according to the predicted power demand.

[0005] Optionally, the energy management and safety control subsystem includes: The multi-source state perception and data fusion unit is used to acquire the state parameters of the aircraft, environmental parameters, hydrogen pressure after pressure regulation, temperature of the aluminum water reactor, oxygen supply parameters of the seawater oxygenation and oxygen supply subsystem, power parameters of the fuel cell stack, and product collection status and historical power sequence of the product processing and water circulation subsystem. The load prediction unit is used to determine the predicted power demand based on the aircraft's state parameters, environmental parameters, hydrogen pressure after pressure regulation, temperature of the aluminum water reactor, oxygen supply parameters of the seawater oxygenation and oxygen supply subsystem, power parameters of the fuel cell stack, and product collection status and historical power sequence of the product processing and water circulation subsystem. The power gap determination unit is used to determine the actual output power of the fuel cell stack, the sustainable output power of the fuel cell stack, and the current maximum output power of the auxiliary energy storage unit; based on the actual output power of the fuel cell stack, the sustainable output power of the fuel cell stack, and the current maximum output power of the auxiliary energy storage unit, it determines the current available power; and based on the predicted power demand and the current available power, it determines the positive power gap. The mode decision unit is used to determine the mode of the aircraft based on the positive power gap, and issue control commands to the aluminum water reactor, hydrogen pressure regulation and supply unit, seawater oxygenation and oxygen supply subsystem, fuel cell stack, waste heat recovery and thermal management subsystem or product processing and water circulation subsystem.

[0006] Optionally, the energy management and safety control subsystem also includes: The environmental and oxygen supply condition assessment unit is connected to the multi-source state sensing and data fusion unit. It is used to assess the oxygen supply capacity of the seawater oxygen supply branch based on the dissolved oxygen concentration, oxygen partial pressure, seawater flow rate, oxygen enrichment chamber status and cathode oxygen demand, and output the oxygen supply capacity assessment results to the model decision unit. The system health status diagnosis unit is connected to the multi-source status perception and data fusion unit. It is used to detect anomalies based on the vehicle's status parameters, environmental parameters, hydrogen pressure after pressure regulation, temperature of the aluminum water reactor, oxygen supply parameters of the seawater oxygenation and oxygen supply subsystem, power parameters of the fuel cell stack, leakage monitoring signals, and product collection status of the product processing and water circulation subsystem. When an abnormal data is detected, the vehicle's safety interlock unit is invoked.

[0007] Optionally, based on the positive power deficit, the vehicle's mode is determined, and corresponding control commands are issued to the aluminum water reactor, hydrogen pressure regulation and supply unit, seawater oxygenation and supply subsystem, fuel cell stack, waste heat recovery and thermal management subsystem, or product processing and water circulation subsystem, including: Based on the positive power gap, the hydrogen pressure after pressure regulation, the oxygen partial pressure, the dissolved oxygen concentration in seawater, the auxiliary energy storage SOC, the temperature of the fuel cell stack, the temperature of the aluminum water reactor, the product collection status, the liquid level of the liquid collection and distribution unit, and the liquid level of the product water collection unit, the mode of the aircraft is determined, and the corresponding outputs of hydrogen production intensity, oxygen supply mode, fuel cell stack power, auxiliary energy storage unit power, DC / DC output current, electrolyte circulation flow rate, spray duty cycle, input ratio of thermal management and waste heat distribution unit, or opening degree of drainage branch are determined.

[0008] Optionally, the hydrogen pressure regulating and supply unit includes a first pressure reducing valve, a hydrogen pressure sensor, a buffer pressure regulating chamber, and a first solenoid valve connected in sequence. The inlet of the buffer pressure regulating chamber is connected to the gas outlet of the gas-liquid separator. The first pressure reducing valve is connected to the buffer hydrogen storage tank, and the first solenoid valve is connected to the anode of the fuel cell stack.

[0009] Optionally, the seawater oxygenation and oxygen supply switching subsystem includes a biomimetic artificial gill module, and the outlet end of the biomimetic artificial gill module is connected in sequence to an oxygen enrichment chamber and a vacuum pump. The vacuum pump is connected to the fuel cell stack via an oxygen supply control valve, which is also connected to a secondary oxygen supply branch. The oxygen supply control valve is used to switch between the vacuum pump and the secondary oxygen supply branch.

[0010] Optionally, the waste heat recovery and thermal management subsystem includes: The dual-plate closed-channel heat exchanger has a first inlet connected to the hydrogen pressure regulation and supply unit, forming a hydrogen preheating branch; a second inlet connected to the seawater oxygenation and oxygen supply switching subsystem, forming an oxidant preheating branch; and both the first and second outlets connected to the fuel cell power generation system. The thermal management and waste heat distribution unit has its inlet end connected to the circulating electrolyte tank and the exhaust gas outlet of the fuel cell stack, respectively, and its outlet end connected to the double-plate closed-circuit heat exchanger and the equipment compartment heat exchanger, respectively. The thermal management and waste heat distribution unit is also electrically connected to the energy management and safety control subsystem. It is used to input the circulating electrolyte into the equipment compartment heat exchanger and the exhaust gas of the fuel cell stack into the double-plate closed-circuit heat exchanger according to the instructions of the energy management and safety control subsystem in the cold start auxiliary preheating mode, and to adjust the input ratio.

[0011] Optionally, the product treatment and water circulation subsystem includes: The liquid collection and separation unit is connected to the aluminum water reactor at the inlet and to the aluminum hydroxide precipitator and Al(OH)3 collection chamber at the outlet in sequence. The water collection unit has an inlet connected to the fuel cell stack and an outlet connected in sequence to an ultrafiltration membrane treatment unit, a pure water buffer tank, and a water pump. The output end of the water pump is connected to the aluminum water reactor, the auxiliary cooling branch, and the discharge branch, respectively.

[0012] Compared with the prior art, the beneficial effects of this application are as follows: This invention relates to an aluminum-water battery-fuel cell hybrid power system for autonomous underwater vehicles. Hydrogen is generated through an aluminum-water reactor, and oxygen is provided by a seawater oxygenation and supply subsystem. This oxygen is then fed into the fuel cell stack to generate electricity. The hydrogen supply from the aluminum-water reactor addresses the safety risks and structural complexity of high-pressure hydrogen storage solutions. The oxygen supply from the seawater oxygenation and supply subsystem avoids the problems associated with oxygen storage solutions, thus solving the problem of insufficient reactant gas supply in fuel cell stacks under deep-sea conditions of low temperature, high pressure, and low dissolved oxygen. A waste heat recovery and thermal management subsystem recovers and utilizes the heat from the electrolyte in the aluminum-water reactor and the exhaust gas from the fuel cell stack. A product processing and water circulation subsystem recovers byproducts from the aluminum-water reactor and purifies and recovers wastewater from the fuel cell stack. An energy management and safety control subsystem controls these subsystems to prevent water management imbalances. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of an aluminum-water battery-fuel cell hybrid power system for an autonomous underwater vehicle according to this application. Figure 2 for Figure 1 Schematic diagram of the hydrogen production subsystem via the water reaction in alumina; Figure 3 for Figure 1 A schematic diagram of the fuel cell power generation system and oxygen supply switching mechanism; Figure 4 for Figure 1 Schematic diagram of the waste heat recovery and thermal management subsystem; Figure 5 for Figure 4 A schematic diagram of a medium-sized open-type waste heat recovery device; Figure 6 for Figure 1 Schematic diagram of the intermediate product treatment and water circulation subsystem; Figure 7 for Figure 1 Control flow diagram of the energy management and safety control subsystem; Figure 8 This is a comparison chart of backup oxygen consumption under low-power cruise conditions in Example 5; Figure 9 This is a comparison chart of startup times under low-temperature startup conditions in Example 5; Figure 10 This is a comparison chart of voltage fluctuation parameters under the DC bus stability condition in Example 5; Figure 11 This is a comparison chart of external water replenishment for the water reuse condition in Example 5; In the diagram, 1. Aluminum-water reaction hydrogen production subsystem, 10. Aluminum-water reactor, 11. Aluminum fuel tank, 12. Gas-liquid separator, 13. Hydrogen purifier, 14. Buffer hydrogen storage tank, 15. Circulating electrolyte tank, 16. Circulating pump, 17. Filter, 18. Second solenoid valve; 2. Hydrogen pressure regulating and supply unit; 21. First pressure reducing valve; 22. Hydrogen pressure sensor; 23. Buffer pressure regulating chamber; 24. First solenoid valve; 3. Seawater oxygenation and oxygen supply subsystem; 31. Bionic artificial gill module; 32. Oxygen-enriched chamber; 33. Micro vacuum pump; 34. Oxygen supply control valve; 35. Pure oxygen supply branch; 36. Air oxygen supply branch. 40. Fuel cell power generation system; 41. Fuel cell stack; 42. Power conversion module; 43. Power conversion and distribution unit; 44. Auxiliary energy storage unit; 45. Load interface; 46. Cooling water tank; 47. Cooling water pump; 48. Radiator. 5. Waste heat recovery and thermal management subsystem, 51. Open waste heat recovery device, 511. Hydrogen preheating branch, 512. Oxidant preheating branch, 513. Equipment compartment heat exchanger, 52. Thermal management and waste heat distribution unit; 6. Product processing and water circulation subsystem; 61. Liquid collection and separation unit; 62. Aluminum hydroxide precipitator; 63. Al(OH)3 collection chamber; 64. Product water collection unit; 65. Ultrafiltration membrane treatment unit; 66. Pure water buffer tank; 67. Water pump; 68. Main reflux branch; 69. Discharge branch; 691. Third check valve; 692. Adjustable membrane valve; 693. Capacitive level sensor; 60. Auxiliary cooling branch; 7. Energy Management and Safety Control Subsystem.

[0014] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] Embodiments of the present invention provide an aluminum-water battery-fuel cell hybrid power system for autonomous underwater vehicles, such as... Figure 1-6As shown, it includes: an aluminum-water reaction hydrogen production subsystem 1, a hydrogen pressure regulation and supply unit 2, a seawater oxygenation and supply subsystem 3, a fuel cell power generation system 4, a waste heat recovery and thermal management subsystem 5, a product processing and water circulation subsystem 6, and an energy management and safety control subsystem 7; the aluminum-water reaction hydrogen production subsystem 1 includes an aluminum-water reactor 10, the fuel inlet of which is connected to an aluminum fuel tank 11, and the reactant outlet is sequentially connected to a gas-liquid separator 12, a hydrogen purifier 13, and a buffer hydrogen storage tank 14, and the liquid outlet of the gas-liquid separator 12 is sequentially connected to a circulating electrolyte. The system includes a tank 15, a circulating pump 16, a filter 17, and a second solenoid valve 18, which is connected to the liquid inlet of the aluminum water reactor 10. A hydrogen pressure regulating and supply unit 2 is connected to a buffer hydrogen storage tank 14 for regulating the output hydrogen pressure. A seawater oxygenation and supply subsystem 3 includes a seawater oxygenation branch and a secondary oxygenation branch. A fuel cell power generation system 4 includes a fuel cell stack 40, whose anode is connected to the hydrogen pressure regulating and supply unit 2, and whose cathode is connected to the seawater oxygenation and supply switching subsystem. The output of the fuel cell stack 40 is sequentially connected to an energy conversion module 4. 1. A power conversion and distribution unit 42 and an auxiliary energy storage unit 43 are provided. The power conversion and distribution unit 42 is equipped with multiple load interfaces 44. The waste heat recovery and thermal management subsystem 5 is connected to the aluminum water reactor 10 and the fuel cell stack 40 respectively, and is used to recover and utilize the heat generated by the electrolyte and the exhaust gas of the fuel cell stack 40. The product treatment and water circulation subsystem 6 is connected to the aluminum water reactor 10 and the fuel cell stack 40 respectively, and is used to recover the by-products generated by the aluminum water reactor 10 and purify and return the wastewater generated by the fuel cell stack 40. The energy management and safety control subsystem 7 is connected to the aluminum-water reaction hydrogen production subsystem 1, hydrogen pressure regulation and supply unit 2, seawater oxygenation and supply subsystem 3, fuel cell power generation system 4, waste heat recovery and thermal management subsystem 5, and product processing and water circulation subsystem 6, respectively. It is used to determine the predicted power demand and issue control commands to the aluminum-water reaction hydrogen production subsystem 1, hydrogen pressure regulation and supply unit 2, seawater oxygenation and supply subsystem 3, fuel cell power generation system 4, waste heat recovery and thermal management subsystem 5, or product processing and water circulation subsystem 6 according to the predicted power demand.

[0017] In this embodiment, hydrogen is generated by the aluminum water reactor 10, and oxygen is provided by the seawater oxygenation and supply subsystem 3. This oxygen is then input into the fuel cell stack 40 to generate electricity. The hydrogen provided by the aluminum water reactor 10 solves the safety risks and structural complexity issues of the high-pressure hydrogen storage scheme. The oxygen provided by the seawater oxygenation and supply subsystem 3 avoids the problems of the oxygen storage scheme, thus solving the problem of insufficient reaction gas supply in the fuel cell stack 40 under deep-sea low temperature, high pressure, and low dissolved oxygen conditions. The waste heat recovery and thermal management subsystem 5 recovers and utilizes the electrolyte heat from the aluminum water reactor 10 and the exhaust gas heat from the fuel cell stack 40. The byproducts generated by the aluminum water reactor 10 are recovered by the product treatment and water circulation subsystem 6, and the wastewater generated by the fuel cell stack 40 is purified and recovered. The above subsystems are controlled by the energy management and safety control subsystem 7 to avoid water management imbalance.

[0018] Specifically, the aluminum molten metal reactor 10 is internally equipped with temperature and pressure sensors, and consists of a gas-liquid separation zone, a spray reaction zone, and a by-product settling zone from top to bottom. The spray reaction zone is equipped with a porous spray pipe or a cyclone distributor, and the bottom by-product settling zone has a by-product discharge structure. The side walls of the aluminum molten metal reactor 10 are equipped with an electrolyte supply port and a water supply port. The aluminum molten metal reactor 10 has a shell-and-tube, tubular, or modular reaction chamber structure, and its interior is equipped with a flow channel structure or jacket structure for controlling spray intensity, liquid distribution uniformity, liquid flow rate, and heat exchange conditions. The by-product discharge structure can be a screw conveyor or a screw slag discharge mechanism to promptly transport the aluminum hydroxide slurry or precipitate to the subsequent collection unit, reducing the risk of flow channel blockage. Aluminum-based fuel is placed in the aluminum fuel tank 11. The aluminum-based fuel can be an Al-Mg-Sn-based alloy, or an aluminum-magnesium alloy, an aluminum-magnesium-tin alloy, or their surface-modified materials. Alternatively, a nano-hydrophobic coating can be formed on the surface of the aluminum fuel to inhibit the formation of a passivation film, reduce ineffective self-corrosion, and improve the controllability of the reaction.

[0019] The electrolyte is a low-concentration alkaline solution or filtered seawater, preferably a 0.5-1.0 mol / L NaOH solution, and the reaction temperature is controlled at 40-80℃. When the electrolyte concentration is below 0.5 mol / L, the reaction activity is improved by adding concentrated electrolyte to the electrolyte supply inlet of the circulating electrolyte tank 15. When the electrolyte concentration is above 1.0 mol / L or the reaction temperature is above 80℃, the speed of the circulating pump 16 is reduced, the cooling bypass is opened, or water is added through the water supply inlet of the circulating electrolyte tank 15 to reduce the risk of corrosion, crystallization and overheating.

[0020] Hydrogen leak sensors, dual rupture discs, electromagnetic pressure relief valves, inert gas purging ports, alkali-resistant sealing rings, and pressure compensation chambers are installed at key locations in the hydrogen production system to improve system operational safety. One-way valves or flame arresters are installed between the gas-liquid separator 12 and the hydrogen purifier 13, and between the hydrogen purifier 13 and the buffer hydrogen storage tank 14, to prevent gas backflow. The outer shells of the circulating electrolyte tank 15 and the aluminum water reactor 10 are made of alkali-resistant corrosion-resistant materials or lined with them. The area between the aluminum water reactor 10 and the gas-liquid separator 12 is primarily a gas-liquid mixture flow channel, and an anti-backflow structure can be installed as needed. The aluminum fuel tank 11 can adopt a drawer-type, silo-type, or box-type replaceable structure. Aluminum-based fuel is arranged in layers within the aluminum fuel tank 11 through limiting grids or porous partitions to ensure that the electrolyte can uniformly contact the aluminum fuel surface. Key locations in the hydrogen production system may include the top of the gas-liquid separation zone or the gas outlet of the aluminum water reactor 10, the outlet of the gas-liquid separator 12, the outlet of the hydrogen purifier 13, the inlet and outlet of the buffer hydrogen storage tank 14, and the inlet or outlet of the hydrogen pressure regulating and supply unit 2.

[0021] The gas-liquid mixture generated in the aluminum molten metal reactor 10 flows into the gas-liquid separator 12. Hydrogen gas, after being purified by the hydrogen purifier 13 to remove alkaline mist, droplets, and particulate impurities, enters the buffer hydrogen storage tank 14. The electrolyte circulation path sequentially consists of a circulating electrolyte tank 15, a circulating pump 16, a filter 17, a spray reaction zone, and a byproduct settling zone, before returning to the gas-liquid separation zone and gas-liquid separator 12 via a return pipeline. A differential pressure sensor is installed between the inlet and outlet of the filter 17. When the differential pressure exceeds a set value, the controller reduces the hydrogen production intensity and performs circulation flushing, bypass reflux, or byproduct discharge. This structure reduces the risk of flow channel blockage caused by aluminum hydroxide deposition and improves the stability of long-term unattended operation. The circulating pump 16 is electrically connected to the energy management and safety control subsystem 7 (mode decision unit) to regulate the electrolyte circulation flow rate. Reducing the hydrogen production intensity can be achieved by decreasing the speed of the circulating pump 16, decreasing the spray duty cycle, decreasing the electrolyte flow rate into the spray reaction zone, and closing the second solenoid valve 18.

[0022] The hydrogen pressure regulating and supply unit 2 includes a first pressure reducing valve 21, a hydrogen pressure sensor 22, a buffer pressure regulating chamber 23, and a first solenoid valve 24 connected in sequence. The inlet of the buffer pressure regulating chamber 23 is connected to the gas outlet of the gas-liquid separator 12. The first pressure reducing valve 21 is connected to the buffer hydrogen storage tank 14, and the first solenoid valve 24 is connected to the anode of the fuel cell stack 40. The hydrogen output from the buffer hydrogen storage tank 14 passes through the first pressure reducing valve 21, the hydrogen pressure sensor 22, and the buffer pressure regulating chamber 23 in sequence to reduce the impact of hydrogen production fluctuations on the stability of the fuel cell stack's hydrogen supply. A one-way valve or flame arrester is installed between the buffer hydrogen storage tank 14 and the first pressure reducing valve 21 to prevent gas backflow. The seawater oxygenation and oxygen supply switching subsystem includes a seawater oxygen supply branch and a secondary oxygen supply branch. Specifically, the seawater oxygen supply branch includes a biomimetic artificial gill module 31, the outlet of which is sequentially connected to an oxygen enrichment chamber 32 and a micro vacuum pump 33. The micro vacuum pump 33 is connected to the fuel cell stack 40 through an oxygen supply control valve 34, which is also connected to the secondary oxygen supply branch. The oxygen supply control valve 34 is used to switch between the seawater oxygen supply branch and the secondary oxygen supply branch. For example, the secondary oxygen supply branch includes a pure oxygen supply branch 35 and an air oxygen supply branch 36, both of which are connected to the oxygen supply control valve 34. The air oxygen supply branch 36 includes an air compressor, an air filter, and a first check valve connected in sequence, which is connected to the oxygen supply control valve 34. The pure oxygen supply branch 35 includes an oxygen cylinder, a second pressure reducing valve, a flow regulating valve, and a second check valve connected in sequence. The oxygen supply control valve 34 is electrically connected to the energy management and safety control subsystem 7 (mode decision unit) for switching oxygen supply modes.

[0023] Specifically, the biomimetic artificial gill module 31 can be composed of multiple membrane modules connected in parallel. The membrane modules adopt a plate, spiral, or hollow fiber structure, and extract dissolved oxygen from the seawater flowing through the module through passive diffusion and micro-vacuum assisted suction. The dissolved oxygen concentration of the extraction environment is preferably 6-8 mg / L. The membrane module material can be silicone rubber, polytetrafluoroethylene composite membrane, hydrophobic microporous membrane, or other oxygen-permeable hydrophobic membrane materials. The effective membrane area, seawater flow rate, and negative pressure of the oxygen-enriching chamber 32 of a single membrane module are determined according to the cruise power requirements of the fuel cell stack 40. The micro-vacuum pump 33 has a power of less than 5W and is used to create a micro-negative pressure in the oxygen-enriching chamber 32 that is lower than that of the external seawater side, thereby improving the dissolved oxygen transmembrane mass transfer efficiency and the stability of cathode oxygen supply. When the pressure or oxygen partial pressure in the oxygen-enriching chamber 32 is lower than the threshold, the speed of the micro-vacuum pump 33 is increased or the auxiliary oxygen supply branch is opened.

[0024] Considering the low dissolved oxygen concentration in seawater, the seawater oxygenation mode of the biomimetic artificial gill module 31 is prioritized for low-power cruise or standby power-saving conditions. Specifically, under low-power cruise or standby power-saving conditions, the energy management and safety control subsystem 7 determines the cathode oxygen demand:

[0025] In the formula, For the first k The fuel cell stack requires 40 tons of cathode oxygen mass flow rate per control cycle. The molar mass of oxygen For the first k The actual output power of the fuel cell stack in one control cycle is 40. F It is Faraday's constant. For the first k The equivalent voltage of a fuel cell cell in each control cycle.

[0026] The amount of extractable oxygen for the seawater oxygen supply branch in the kth control cycle is determined based on the dissolved oxygen concentration, seawater flow rate, oxygen partial pressure in oxygen-enriched chamber 32, and cathode oxygen demand of fuel cell stack 40.

[0027]

[0028] In the formula, The first obtained by estimating the membrane mass transfer mode k The oxygen molar flow rate that can be extracted from the seawater oxygen supply branch in each control cycle For the effective membrane area of ​​the biomimetic artificial gill module 31, Oxygen flux in the form of membrane mass transfer For the first k Oxygenation efficiency per control cycle The equivalent mass transfer coefficient, This refers to the dissolved oxygen concentration in seawater. This is the equilibrium dissolved oxygen concentration corresponding to the oxygen partial pressure of 32 in the oxygen-enriched chamber.

[0029] When considering the upper limit of seawater flow rate, the extractable oxygen mass flow rate also satisfies:

[0030] In the formula, When constrained by the upper limit of seawater flow rate, the first k The oxygen mass flow rate that can be extracted from the seawater oxygen supply branch in each control cycle The density of seawater, For the first k Each control cycle uses the seawater volume flow rate of the biomimetic artificial gill module 31. For the first k Dissolved oxygen concentration in seawater during each control period For the first k The oxygen extraction efficiency for each control cycle. The actual amount of oxygen that can be extracted by the seawater oxygen supply branch used in the model decision unit is the smaller of the membrane mass transfer estimate and the upper limit of oxygen-carrying capacity of the seawater flow rate.

[0031] When the cathode oxygen demand exceeds the current extractable oxygen supply of the bionic artificial gill module 31, the dissolved oxygen concentration of seawater is below a set threshold, the oxygen partial pressure in the oxygen-enriched chamber 32 is insufficient, or the AUV enters a high-power maneuvering mode, the energy management and safety control subsystem 7 switches to the auxiliary oxygen supply branch and limits the power ramp-up rate of the fuel cell stack 40 to avoid cathode hypoxia; the auxiliary oxygen supply branch replenishment amount It can be represented as:

[0032] When the oxygen partial pressure in the seawater oxygenation branch recovers and meets the margin requirements, the energy management and safety control subsystem 7 reduces the flow rate of the auxiliary oxygen supply branch or switches to the seawater oxygenation branch. (Seawater oxygenation contribution ratio) The expression is:

[0033] The parameters of the effective membrane area, seawater flow rate, and negative pressure of the oxygen-enriched chamber 32 in this mode are shown in Table 1. Table 1

[0034] The fuel cell stack 40 uses a PEM fuel cell stack, which has the advantages of fast start-up, high power density, and strong adaptability to varying operating conditions. The stack can adopt a single-stack structure or a modular parallel structure to improve system redundancy and maintenance convenience. The products of the fuel cell stack 40 include electrical energy, heat, and water. The generated electrical energy is fed into the DC bus via the DC / DC power conversion module 41 to power the thrusters, navigation equipment, control equipment, sensors, and mission payloads. The auxiliary energy storage unit 43 and the power conversion module 41 are both connected to the energy management and safety control subsystem 7 (mode decision unit) to receive commands and regulate the power of the fuel cell stack 40 or the DC / DC output current. The fuel cell stack 40 also includes a stack fluid management unit, which includes a cooling water pump 46, a radiator 47, and a cooling water tank 45. The stack fluid of the fuel cell stack 40 enters the cooling water tank 45, forming a circulation between the cooling water tank 45, the cooling water pump 46, the radiator 47, and the cooling water tank 45.

[0035] The waste heat recovery and thermal management subsystem 5 includes an open waste heat recovery device 51, which can be a double-plate closed-channel heat exchanger. The first inlet of the double-plate closed-channel heat exchanger is connected to the hydrogen pressure regulating and supply unit 2, forming a hydrogen preheating branch 511. The second inlet of the double-plate closed-channel heat exchanger is connected to the seawater oxygenation and oxygen supply switching subsystem, forming an oxidant preheating branch 512. Both the first and second outlets are connected to the fuel cell power generation system 4. The thermal management and waste heat distribution unit 52 has its inlet connected to the circulating... The outlets of the circulating electrolyte tank 15 and the fuel cell stack 40 are respectively connected to a double-plate closed-channel heat exchanger and an equipment compartment heat exchanger 513. The thermal management and waste heat distribution unit 52 is also electrically connected to the energy management and safety control subsystem 7. According to the instructions of the energy management and safety control subsystem 7, in the cold start auxiliary preheating mode, it inputs the circulating electrolyte from the circulating electrolyte tank 15 into the equipment compartment heat exchanger 513 and the exhaust gas from the fuel cell stack 40 into the double-plate closed-channel heat exchanger, and adjusts the input ratio. A circulating liquid heat exchanger is also provided between the circulating electrolyte tank 15 and the thermal management and waste heat distribution unit 52. The channels in the double-plate closed-channel heat exchanger are corrugated / bent / serpentine channels. The cold start auxiliary preheating mode is the mode that needs to be switched when starting the aircraft when all equipment in the aircraft is below a preset temperature threshold; that is, the low-temperature cold start auxiliary preheating mode.

[0036] Specifically, the thermal management and waste heat distribution unit 52 includes a first temperature control valve connected between the circulating liquid heat exchanger and the equipment compartment heat exchanger 513, a second temperature control valve located between the exhaust gas outlet of the fuel cell stack 40 and the double-plate closed-loop heat exchanger, a third temperature control valve located between the exhaust gas outlet of the fuel cell stack 40 and the preheating branch of the fuel cell stack 40, and a bypass valve located on the bypass valve exhaust gas outlet pipeline of the fuel cell stack 40. The input ratio is the adjustment of the opening degree of each valve. The thermal management and waste heat distribution unit 52 also includes temperature sensors respectively located in the aluminum water reactor 10, the exhaust gas outlet of the fuel cell stack 40, the outlet of the hydrogen preheating branch 511, the outlet of the oxidant preheating branch 512, and the cold circuit of the equipment compartment heat exchanger 513 of the vessel, for correspondingly collecting reaction heat, exhaust gas waste heat, preheated gas temperature, and equipment compartment temperature. The equipment compartment heat exchanger 513 is used to maintain the operating temperature of key electronic equipment such as navigation computers, sensors, controllers, and valve pump actuators. When preheating is required during low-temperature start-up, deep-diving at low temperatures, or high-load conditions, the first, second, and third temperature control valves are opened. When each temperature sensor detects that the corresponding temperature has reached the set range or rapid cooling is required, the first, second, and third temperature control valves are closed and the bypass branch is opened.

[0037] The product processing and water circulation subsystem 6 includes a liquid collection and distribution unit 61. The inlet of the liquid collection and distribution unit 61 is connected to the aluminum water reactor 10 through a by-product conveying channel, and the outlet is sequentially connected to an aluminum hydroxide precipitator 62 and an Al(OH)3 collection chamber 63. The inlet of the product water collection unit 64 is connected to the drainage channel of the fuel cell stack 40, and the outlet is sequentially connected to an ultrafiltration membrane treatment unit 65, a pure water buffer tank 66, and a water pump 67. The output end of the water pump 67 is connected to the main reflux branch 68 (aluminum water reactor 10), the auxiliary cooling branch 60, and the discharge branch 69. The discharge branch 69 is sequentially equipped with a third check valve 691, an adjustable membrane valve 692, and a capacitive liquid level sensor 693 to achieve protection against seawater backflow during tail discharge.

[0038] For example, the Al(OH)3 collection chamber 63 is replaceable and is a sealed storage structure. Its capacity is determined based on the aluminum fuel loading, theoretical by-product generation, and sedimentation water content, and can support the system to operate continuously for at least 50 hours. When the liquid level or pressure difference of the Al(OH)3 collection chamber 63 reaches the threshold, the energy management and safety control subsystem 7 reduces the hydrogen production rate or switches to a safety degradation mode.

[0039] The water generated by the fuel cell stack 40 first enters the product water collection unit 64, then passes through the ultrafiltration membrane treatment unit 65 to remove particulate matter and impurities. Subsequently, it is distributed by the water pump 67 to: the main return branch 68, which returns the water to the water replenishment interface of the aluminum water reactor 10 to maintain system water balance and reaction water replenishment; the auxiliary cooling branch 60, used for cooling the AUV electronic compartment or equipment compartment; and the discharge branch 69, used to discharge redundant pure water through the external discharge port. The discharge branch 69 is equipped with a third check valve 691, an adjustable membrane valve 692, and a capacitive liquid level sensor 693 to achieve backflow protection against seawater intrusion. The product processing and water circulation subsystem 6 can calculate the theoretical water consumption of the fuel cell stack 40, the amount of reclaimable water, and the amount of external replenishment water according to the material closed-loop relationship, as detailed below: Based on the hydrogen-oxygen fuel cell reaction, the amount of water generated by fuel cell stack 40 It can be represented as:

[0040] In the formula, This refers to the mass of hydrogen consumed by the fuel cell stack 40 under the corresponding operating conditions. Based on the stoichiometric relationship of the aluminum molten metal reaction, the theoretical water consumption of aluminum molten metal reactor 10 is... It can be represented as:

[0041] When the water generated by the fuel cell stack is reused at a rate of 40%, At that time, the amount of water that can be recycled and external water supply They can be represented as:

[0042]

[0043] Compared to a scheme that does not reuse the fuel cell stack to generate water, the reduction in external water replenishment can be expressed as:

[0044] like Figure 7 As shown, the energy management and safety control subsystem 7 includes a multi-source state perception and data fusion unit, a load prediction unit, a power gap determination unit, and a mode decision unit; wherein, the multi-source state perception and data fusion unit is used to acquire the vehicle's state parameters, environmental parameters, hydrogen pressure after pressure regulation, temperature of aluminum water reactor 10, oxygen supply parameters of seawater oxygenation and oxygen supply subsystem 3, electrical energy parameters of fuel cell stack 40, and product collection status, leakage monitoring signals (hydrogen concentration / leakage monitoring) and historical power sequences of product processing and water circulation subsystem 6; For example, the state parameters of the aircraft include speed, depth, attitude, propulsion power requirements and mission payload status; environmental parameters include ambient temperature; the oxygen supply parameters of the seawater oxygenation and oxygen supply subsystem 3 include dissolved oxygen concentration and oxygen partial pressure of seawater; the electrical energy parameters of the fuel cell stack 40 (stack) include voltage, current and temperature; and the product collection status of the water circulation subsystem includes the liquid level or pressure difference of Al(OH)3 collection tank 63, the liquid level of liquid collection and distribution unit 61 and the liquid level of product water collection unit 64.

[0045] The load prediction unit is used to determine the predicted power demand based on the aircraft's state parameters, environmental parameters, hydrogen pressure after pressure regulation, temperature of aluminum water reactor 10, oxygen supply parameters of seawater oxygenation and oxygen supply subsystem 3, power parameters of fuel cell stack 40, and product collection status and historical power sequence of product processing and water circulation subsystem 6. Specifically, power demand is predicted using a pre-trained load prediction model. This model can be a Long Short-Term Memory (LSTM) network, requiring only pre-training. The k-th control cycle is input into the multi-source features, represented as:

[0046] This represents the multi-source state feature vector of the input load prediction unit in the k-th control cycle; Indicates speed; Indicates depth; Indicates the rate of change of attitude; Indicates the power requirement for propulsion; Indicates the mission payload status; This represents a historical power sequence of length m; Indicates ambient temperature; Indicates the dissolved oxygen concentration in seawater; Indicates the partial pressure of oxygen; Indicates hydrogen pressure; This indicates the temperature of aluminum molten metal reactor 10; This indicates a 40V fuel cell stack. This indicates a current of 40 kW for the fuel cell stack. Indicates liquid level or water level signal; This represents the transpose of a vector.

[0047] The predicted power demand for the next N steps is expressed as:

[0048] in, For the predicted power demand sequence over the next N steps; f (·) represents the nonlinear mapping relationship given by the pre-trained load prediction model.

[0049] The predicted power demand is then corrected in real time, and the corrected predicted power demand is expressed as follows:

[0050] In the formula, The output value of the pre-trained load prediction model. The feedback correction amount can be obtained by limiting or filtering the deviation between the actual load power and the corresponding predicted power demand from one or more recent control cycles, for example... λ is the feedback correction coefficient; when feedback correction is not used... Take 0.

[0051] The power gap determination unit is used to determine the actual output power of the fuel cell stack 40, the sustainable output power of the fuel cell stack 40, and the current maximum output power of the auxiliary energy storage unit 43, respectively; and to determine the current available power based on the actual output power of the fuel cell stack 40, the sustainable output power of the fuel cell stack 40, and the current maximum output power of the auxiliary energy storage unit 43. ;

[0052] In the formula, The rated power of the fuel cell stack 40, This represents the upper limit of the sustainable output power of the fuel cell stack 40 when hydrogen supply is constrained. The upper limit of the sustainable output power of the fuel cell stack 40 when oxygen supply is constrained; To assist the current maximum output power of the energy storage unit 43, The upper limit of power is constrained by thermal management capabilities. This represents the upper limit of sustainable output power obtained from system health state constraints. When constrained by hydrogen supply, the upper limit of sustainable output power of fuel cell stack 40 is expressed as:

[0053] In the formula, For the system efficiency of fuel cell stack 40, The lower heating value of hydrogen. This represents the allowable hydrogen mass flow rate for the kth control cycle.

[0054] When oxygen supply is constrained, the upper limit of the sustainable output power of the fuel cell stack 40 is expressed as follows:

[0055] In the formula, F is the Faraday constant. The equivalent average voltage. This represents the molar flow rate of oxygen participating in the reaction. If... Defined as the molar oxygen flow rate of a single cell, it can be expressed as:

[0056] In the formula, This refers to the number of individual cells connected in series in a fuel cell stack. For the first k The equivalent average operating voltage of a single battery cell within a control cycle.

[0057] The maximum output power of the auxiliary energy storage unit 43 can be expressed as:

[0058] In the formula, To support the rated output power of the auxiliary energy storage unit 43, The current state of charge, To allow the lowest possible state of charge, For auxiliary energy storage capacity, Δt is the control cycle length.

[0059] The actual output power of the fuel cell stack 40 can be expressed as:

[0060] In the formula, This refers to the output voltage of the fuel cell stack 40. This is the output current of the fuel cell stack 40.

[0061] Based on the predicted power demand and the current available power, the positive power gap is determined; for the j-th prediction step within the prediction window, the positive power gap can be expressed as:

[0062] The maximum positive power gap within the prediction window can be expressed as:

[0063] The mode decision unit is used to determine the mode of the aircraft based on the positive power gap, and issue control commands to the aluminum water reactor 10, hydrogen pressure regulation and supply unit 2, seawater oxygenation and oxygen supply subsystem 3, fuel cell stack 40, waste heat recovery and thermal management subsystem 5 or product processing and water circulation subsystem 6.

[0064] Specifically, the mode decision unit determines the vehicle's mode based on the positive power gap, the hydrogen pressure after pressure regulation, the oxygen partial pressure, the dissolved oxygen concentration in seawater, the SOC of the auxiliary energy storage unit 43, the temperature of the fuel cell stack 40, the temperature of the aluminum water reactor 10, the product collection status, and the liquid level inside the cabin. It then outputs the hydrogen production intensity, oxygen supply mode, power of the fuel cell stack 40, power of the auxiliary energy storage unit 43, DC / DC output current, electrolyte circulation flow rate (controlled by the electrolyte circulation pump 16), and the input ratio of the thermal management and waste heat distribution unit 52 (the opening degree of each temperature control valve) or the opening degree of the drainage branch. Among them, the oxygen partial pressure is the oxygen partial pressure of the seawater oxygenation and oxygen supply subsystem 3, which can be obtained by the oxygen partial pressure sensor at the cathode inlet of the oxygen enrichment chamber 32, the downstream pipeline of the oxygen supply control valve 34, or the fuel cell stack 40; the liquid level inside the cabin is the liquid level monitoring value of the internal drainage branch or the tail discharge safety branch of the aircraft; the power adjustment command of the fuel cell stack 40 is adjusted on the power side through the output current command of the power conversion module 41, and the reactant supply is matched with the opening degree of the first solenoid valve 24, the state of the oxygen supply control valve 34, and the oxygen supply flow rate adjustment of the micro vacuum pump 33 or the air compressor.

[0065] For example, the hydrogen production intensity, the power of the fuel cell stack 40, the power of the auxiliary energy storage unit 43, the electrolyte circulation flow rate, the spray duty cycle, and the opening degree of the temperature control valve can all be generated using one or more of the following methods: saturation function, proportional correction, lookup table control, or closed-loop control. The opening actions of the oxygen supply mode and the drainage branch can be generated using threshold judgment, state machine, or safety interlock rules. The aforementioned saturation function, proportional correction, lookup table control, closed-loop control, threshold judgment, and state machine can all be implemented using existing control methods. This application does not limit the specific algorithm structure; its function is to generate the control quantities of the corresponding actuators based on the state quantities collected by this system.

[0066] The vehicle's mode switching conditions are as follows: if the predicted power demand is lower than the cruise threshold and the seawater oxygenation capacity (including the amount of extractable oxygen and the dissolved oxygen concentration of seawater) meets the cathode oxygen demand, then it enters the high-efficiency cruise mode; if the predicted power demand is higher than the maneuver threshold or the rate of increase of the predicted power demand exceeds the set value, then it enters the high-power maneuver mode; if the hydrogen pressure, oxygen partial pressure, aluminum water reactor 10 temperature, fuel cell voltage, or Al(OH)3 collection tank 63 liquid level exceeds the limit, then it enters the safety degrading mode.

[0067] Furthermore, the energy management and safety control subsystem 7 also includes an environmental and oxygen supply condition assessment unit and a system health status diagnosis unit. The environmental and oxygen supply condition assessment unit is used to determine whether the seawater oxygen supply branch meets the oxygen supply margin based on the dissolved oxygen concentration, oxygen partial pressure, seawater flow rate, oxygen enrichment chamber 32 status and cathode oxygen demand, and outputs the oxygen supply capacity assessment results to the mode decision unit.

[0068] The system health status diagnosis unit is used to detect anomalies based on the aircraft's status parameters, environmental parameters, hydrogen pressure after pressure regulation, temperature of the aluminum water reactor 10, oxygen supply parameters of the seawater oxygenation and oxygen supply subsystem 3, electrical energy parameters of the fuel cell stack 40, leakage monitoring signals, and product collection status of the product processing and water circulation subsystem 6. When an anomaly is detected, the system invokes the aircraft's safety interlock unit to perform actions such as load reduction, switching oxygen storage / enhanced oxygen supply, shutting down hydrogen production, isolating faulty branches, activating drainage protection, stopping / switching the auxiliary energy storage unit 43, or triggering alarms and return / surfacing strategies. Types of data anomalies may include hydrogen leakage, insufficient oxygen supply, excessively high temperature of the aluminum water reactor 10, abnormal voltage, current, or temperature of the fuel cell stack 40, or abnormal liquid level. The safety interlock unit is part of the aircraft's control system; this embodiment only requires invocation. Leakage monitoring signals are signals output by hydrogen concentration sensors or leakage sensors located near the anode inlet of the aluminum water reactor 10, gas-liquid separator 12, hydrogen purifier 13, buffer hydrogen storage tank 14, hydrogen pressure regulating and supply unit 2, or fuel cell stack 40; abnormal liquid levels include abnormal liquid level or pressure difference in Al(OH)3 collection chamber 63, abnormal liquid level in liquid collection and distribution unit 61, abnormal liquid level in product water collection unit 64, and abnormal liquid level in drainage branch or tail discharge safety branch.

[0069] Specifically, the intelligent energy management and safety control subsystem 7 can be controlled according to the following triggering conditions and execution actions. This triggering action relationship illustrates an implementable control logic, and those skilled in the art can adjust the thresholds based on the platform size, the power level of the fuel cell stack 40, and the mission profile. Further, each threshold can be pre-calibrated based on the platform power level, the rated power of the fuel cell stack 40, the oxygen supply capacity of the artificial gills, the auxiliary energy storage capacity, and the mission profile. To enhance the supportability of the specification, in one embodiment, each threshold can be set according to the following principles, as shown in Tables 2 and 3: Table 2

[0070] The above threshold range is only an exemplary calibration principle. Specific values ​​can be adjusted according to the size of the aircraft, the power level of the fuel cell stack, the area of ​​the membrane module, the oxygen storage capacity, and the marine environment of the operating area.

[0071] Table 3

[0072] Example 1 The aluminum fuel in the aluminum fuel tank 11 is made of Al-Mg-Sn based alloy plate with a nano-hydrophobic coating on the surface. Seawater or low-concentration alkaline solution is pre-adjusted to a set concentration before entering the circulating electrolyte tank 15 or being metered into the circulating electrolyte tank 15 via replenishment or concentration, and then sent to the aluminum water reactor 10 by the circulating pump 16. The circulation speed is regulated by the rotational speed of the circulating pump 16 and the opening of the second solenoid valve 18. The reaction temperature is regulated by the spray duty cycle of the aluminum water reactor 10, the circulating liquid heat exchanger, and the first temperature control valve. The upper spray distribution structure of the aluminum water reactor 10 is used to adjust the reaction contact area and wetting state, thereby achieving controllable adjustment of the hydrogen production rate through closed-loop control of electrolyte concentration, flow rate, and reaction temperature.

[0073] The hydrogen generated by the aluminum water reactor 10 is separated into droplets by the gas-liquid separator 12 and then enters the hydrogen purifier 13 to remove alkaline mist and particulate impurities before entering the buffer hydrogen storage tank 14. Subsequently, it is sent to the anode inlet of the fuel cell stack 40 through the first pressure reducing valve 21, pressure sensor, pressure stabilizing buffer chamber and the first solenoid valve 24.

[0074] The fuel cell stack 40 uses a PEM fuel cell stack. Cathode oxygen supply preferentially utilizes the seawater oxygenation branch. The biomimetic artificial gill module 31 has a built-in silicon-based hydrophobic / oxygen-permeable composite membrane in its artificial gills, and the auxiliary micro-vacuum pump 33 has a power of less than 5W to improve transmembrane oxygen transfer efficiency. When deep diving, high-maneuvering, seawater dissolved oxygen levels decrease, or the oxygen partial pressure in the oxygen-enriched chamber 32 falls below the threshold, the oxygen supply control valve 34 opens the backup auxiliary oxygen supply branch.

[0075] The exhaust gas from the fuel cell stack 40 enters a dual-plate closed-circuit heat exchanger, whose internal corrugated or sinusoidal channels enhance exhaust gas turbulence and heat exchange area. The exhaust gas heat is simultaneously transferred through a high thermal conductivity layer to the hydrogen preheating branch 511 and the oxidant preheating branch 512, preheating the reaction gases before they enter the stack. At the same time, the circulating liquid in the aluminum molten reactor 10 transfers the reaction heat to the equipment compartment liquid cooling circuit, providing insulation and heating for the AUV electronic equipment.

[0076] The aluminum hydroxide slurry, a byproduct of the aluminum molten metal reaction, is conveyed by a screw conveyor at the bottom of the reactor and enters the Al(OH)3 collection chamber 63 via the collection and separation unit 61 and the aluminum hydroxide precipitator 62. The collection chamber 63 has a capacity to support continuous operation of the system for no less than 50 hours and allows for recovery, replacement, or centralized treatment at the water surface.

[0077] The generated water from the fuel cell stack 40 enters the water collection unit 64, is purified by the ultrafiltration membrane treatment unit 65, and is then distributed by the water pump 67: a portion flows back to the water supply interface of the aluminum water reactor 10 to maintain water balance; another portion is used for cooling the AUV electronic cabin; and the remainder is discharged through the drainage branch of the third check valve 691, the adjustable membrane valve 692, and the capacitive liquid level sensor 693 to prevent seawater backflow.

[0078] The intelligent energy management module collects real-time data on speed, depth, attitude, propulsion power demand, mission load status, ambient temperature, dissolved oxygen concentration or oxygen partial pressure, hydrogen pressure, temperature of the aluminum molten reactor 10, voltage and current of the fuel cell stack 40, product collection status, and leakage monitoring signals. This data is then input into the load prediction unit. The load prediction unit first uses LSTM to determine the predicted power demand based on historical power sequences and the current mission status, and then determines the positive power gap. Based on the positive power gap and the current system status, it dynamically adjusts the aluminum molten reactor intensity, the output power of the fuel cell stack 40, the oxygen supply mode, heat distribution, and drainage strategy.

[0079] Example 2: Implementation of Enhanced Thermal Management under Cryogenic Deep-Sea Submersion Conditions During cryogenic deep-sea diving missions, the ambient seawater temperature is low, and the electronic equipment and fuel cell stack 40 are at risk of temperature drop in reaction activity. The thermal management and waste heat distribution unit 52 prioritizes the transfer of the heat from the aluminum molten metal reaction and the heat from the fuel cell stack exhaust gas to the hydrogen preheating branch 511, the oxidant preheating branch 512, and the equipment compartment heat exchanger 513. The hydrogen preheating branch 511, the oxidant preheating branch 512, and the equipment compartment heat exchanger 513 constitute the cryogenic cold start auxiliary preheating branch.

[0080] The heat carried out by the circulating electrolyte in the aluminum water reactor 10 serves as one of the heat sources for the low-temperature cold start auxiliary preheating branch, while the heat recovered from the anode and cathode exhaust gases of the fuel cell stack 40 by the open waste heat recovery device 51 serves as another heat source. After being collected and isolated by the thermal management and waste heat distribution unit 52, the two are distributed to the low-temperature cold start auxiliary preheating branch as needed.

[0081] The available heat input during the low-temperature cold start phase can be expressed as:

[0082] In the formula, This indicates the available waste heat entering the thermal management and waste heat distribution unit 52; This represents the heat of reaction output from the aluminum molten metal reactor 10 via the circulating electrolyte; This indicates the waste heat from the anode and cathode exhaust gases of the fuel cell stack 40, which is recovered by the waste heat recovery device.

[0083] The preheating heat output of the low-temperature cold start auxiliary preheating branch can be expressed as:

[0084] In the formula, This indicates the total preheating heat output by the low-temperature cold start auxiliary preheating branch; This indicates the heat obtained by the hydrogen preheating branch 511, which is used to increase the hydrogen temperature at the anode inlet. This indicates the heat obtained by the oxidant preheating branch 512, which is used to increase the oxidant temperature at the cathode inlet; This indicates the heat obtained by the equipment compartment heat exchanger 513, which is used to maintain the operating temperature of the controller, navigation computer, and sensors. This indicates that the heat obtained by the fuel cell stack 40 or the coolant preheating branch is used to quickly bring the stack into its effective operating temperature range. The heat obtained by the fuel cell stack 40 or the coolant preheating branch is indirectly transferred to the fuel cell stack 40 by the thermal management and waste heat distribution unit 52, which inputs the heat from the aluminum-water reaction or the waste heat from the exhaust gas of the fuel cell stack 40 into the stack coolant preheating branch or the coolant heat exchanger, thus preventing the hydrogen, oxidant, or exhaust gas from mixing.

[0085] The distribution relationship of the thermal management and waste heat distribution unit 52 to each preheating branch can be expressed as follows:

[0086] In the formula, This represents the heat obtained by the i-th preheating branch; This represents the heat distribution coefficient of the i-th preheating branch, which is determined by the opening degree of the temperature control valve group, the branch flow rate, and the target temperature.

[0087] The entry and exit conditions for the low-temperature cold start auxiliary preheating mode can be expressed as follows:

[0088] In the formula, Indicates the status of the low-temperature cold start auxiliary preheating mode; This indicates that the system has entered the low-temperature cold start auxiliary preheating mode. This indicates that you are exiting this mode; Indicates the ambient seawater temperature; This indicates the threshold for determining low-temperature environments; This indicates the fuel cell stack temperature at 40°C. , This indicates the minimum start-up temperature of the fuel cell stack at 40°C. , This indicates the target operating temperature of the fuel cell stack at 40°C. Indicates the temperature of the equipment compartment; , This indicates the target insulation temperature of the equipment compartment.

[0089] During low-temperature cold start, the heat dissipation bypass branch is closed or reduced, and the low-temperature cold start auxiliary preheating branch is opened first. After the system enters stable cruise, the thermal management and waste heat distribution unit 52 dynamically adjusts the flow ratio of each branch according to the equipment compartment temperature, power compartment temperature, circulating fluid temperature and fuel cell stack temperature, so as to balance heat preservation and heat dissipation.

[0090] Example 3: Implementation of Power Cooperative Control under High-Load Mobility Conditions When the AUV performs rapid turning, acceleration, climbing, or obstacle avoidance tasks, the energy management and safety control subsystem 7 enters a high-power maneuvering mode based on load prediction results. At this time, the mode decision unit performs the following actions: 1. Increase the electrolyte circulation flow rate and spray intensity to increase the aluminum molten metal reaction rate; 2. Open the buffer hydrogen storage branch to improve the dynamic response of hydrogen supply; wherein, the buffer hydrogen storage branch refers to the hydrogen supply branch that is sequentially connected to the anode inlet of the fuel cell stack 40 by the buffer hydrogen storage tank 14, the first pressure reducing valve 21, the hydrogen pressure sensor 22, the buffer pressure regulating chamber 23 and the first solenoid valve 24.

[0091] 3. By increasing the opening degree of the first solenoid valve 24, increasing the oxygen supply flow rate, adjusting the DC / DC output current command, and maintaining the temperature of the fuel cell stack 40 within the set operating range, the output power of the fuel cell stack 40 is increased, enabling the stack to bear the main peak power output; wherein, the DC / DC output current command is used to adjust the electrical power output of the fuel cell stack 40 to the DC bus, and the opening degree of the first solenoid valve 24 and the oxygen supply flow rate are used to match the increased anode hydrogen supply and cathode oxygen supply.

[0092] 4. Selectively utilize small lithium-ion buffer batteries for transient compensation; 5. When the seawater oxygenation capacity is insufficient, switch to the auxiliary oxygen supply branch; 6. Simultaneously, increase the intensity of waste heat recovery preheating to maintain a stable reactor stack reaction temperature. Increasing the intensity of waste heat recovery preheating can be achieved by increasing the opening degree of the temperature control valves corresponding to the hydrogen preheating branch 511, the oxidant preheating branch 512, and the reactor stack or coolant preheating branch, or by decreasing the opening degree of the heat dissipation bypass branch.

[0093] The above controls can meet the transient power requirements of AUVs for high-mobility missions.

[0094] Example 4: Implementation of Safety Interlock Control under Abnormal Operating Conditions When the system health status diagnosis unit detects hydrogen leakage, insufficient oxygen supply, reactor overheating, flow channel blockage, individual stack abnormality, abnormal liquid level, or seawater backflow risk, the safety interlock unit automatically executes graded protection actions, including but not limited to: 1. Reduce the output power of the fuel cell stack by 40; 2. Turn off the reactor spray or reduce the electrolyte circulation flow rate; 3. Disconnect part or all of the hydrogen supply branches; 4. Switch to enhanced oxygen supply mode or isolate the abnormal oxygen supply branch; 5. Activate drainage protection and close high-risk tailpipe valve positions; 6. Activate auxiliary energy storage to provide backup power; 7. In the event of a severe failure, execute the shutdown, return to base, or surface strategy.

[0095] The above interlocking process ensures that the AUV still has a minimum power maintenance and safe exit capability under abnormal operating conditions.

[0096] Example 5: Parametric Simulation Verification under Typical Operating Conditions To further illustrate the impact of the seawater oxygenation priority supply, waste heat recovery preheating, predictive energy management, auxiliary energy storage coordination control, and water reuse of the fuel cell stack 40 on the operation of the autonomous underwater vehicle hybrid power system, a parameterized simulation example under typical operating conditions is established in this embodiment.

[0097] I. Simulation assumptions, see Table 4 Table 4

[0098] I. Low-power cruise operation In this simulation example, low-power cruise lasts for 10 hours, with fuel cell stack 40 outputting 300 W at an efficiency of 50%. The hydrogen consumption of fuel cell stack 40 is... Calculate using the following formula:

[0099] In the formula, This refers to the electrical energy output of the fuel cell stack 40 under low-power cruise conditions. For fuel cell stacks with an efficiency of 40%, This is the lower heating value of hydrogen.

[0100] Oxygen consumption Calculate using the following formula:

[0101] Therefore, the total oxygen requirement for cruise operation is 1.440 kg. The baseline scheme relies entirely on the backup oxygen source, which consumes 1.440 kg. In this invention, the seawater oxygen supply branch handles 65% of the oxygen requirement, and the secondary oxygen supply branch handles 35%. The secondary oxygen supply branch consumes 0.504 kg, and its oxygen contribution is 0.936 kg. The reduction in consumption by the secondary oxygen supply branch is calculated using the following formula:

[0102] The oxygen contribution ratio of the seawater oxygen supply branch is calculated using the following formula: To further illustrate the calculation boundary of seawater oxygenation capacity, under the aforementioned oxygen demand, the seawater oxygen supply branch needs to provide 0.936 kg of oxygen. If the dissolved oxygen concentration in the seawater is taken as 7 mg / L, the equivalent seawater flow rate through the oxygenation channel during navigation is taken as 420 L / min, and the oxygenation efficiency is taken as 53.1%, then the seawater oxygenation amount within 10 hours can be estimated using the following formula:

[0103] In the formula, The mass of oxygen that can be extracted from the seawater oxygen supply branch during the calculation period. The equivalent seawater flow rate through the oxygen intake channel. This refers to the dissolved oxygen concentration in seawater. For calculating the time period, To improve oxygenation efficiency.

[0104]

[0105] The above calculations show that the 65% seawater oxygenation contribution ratio in this simulation example corresponds to a relatively high water flow rate and oxygenation efficiency, making it suitable for low-power cruising scenarios with upstream or pump-assisted water intake. When the cruising speed, water flow rate, or membrane mass transfer performance decreases, the seawater oxygenation contribution ratio should be reduced and the supplementary amount of the enhanced oxygen supply branch should be increased, as detailed in [link to relevant documentation]. Figure 8 and Table 5;

[0106] Table 5

[0107] Depend on Figure 8 As shown in Table 5, under low-power cruise conditions, the baseline scheme's backup oxygen consumption is 1.440 kg, while the scheme of this invention consumes only 0.504 kg, representing a 65.0% reduction in backup oxygen consumption. Simultaneously, the seawater oxygen supply branch provides 0.936 kg of oxygen, contributing 65.0% to the oxygen supply. This indicates that when upstream water intake or pump-assisted water intake is available, the seawater oxygen supply and switching subsystem can handle the main cathode oxygen demand, significantly reducing reliance on backup oxygen sources. This helps reduce the burden on oxygen storage and improves the endurance adaptability under low-power cruise conditions.

[0108] II. Low Temperature Start-up Condition In this simulation example, the ambient temperature is 2 ℃, and the target start-up temperature of the fuel cell stack 40 is 45 ℃. The baseline scheme, without waste heat recovery preheating, takes 35 minutes to reach the target operating temperature. The system of this invention uses the heat of the aluminum molten metal reaction and the waste heat from the fuel cell stack exhaust gas for preheating. According to the heat balance model, preheating here refers to the process where the heat of the aluminum molten metal reaction and the waste heat from the fuel cell stack 40 exhaust gas are recovered by the thermal management and waste heat distribution unit 52, and then indirectly increase the inlet reaction gas temperature and the fuel cell stack coolant temperature of the fuel cell stack 40 through the hydrogen preheating branch 511, the oxidant preheating branch 512, and the fuel cell stack coolant preheating branch.

[0109]

[0110] in, For the equivalent heat capacity, take 18 kJ / K; ΔT = 43 K; The equivalent heating power of the baseline scheme is 368.57 W, calculated backwards from the baseline start-up time. Assuming the usable power from waste heat is 348.10 W, the calculated start-up time is 18.00 min. The percentage reduction in start-up time is calculated using the following formula:

[0111] The hydrogen inlet temperature was increased from 4.00 ℃ to 28.00 ℃, and the oxidant inlet temperature was increased from 4.00 ℃ to 26.00 ℃.

[0112] In the parametric simulation of thermal management, the equivalent heating power of the baseline scheme is 368.57 W. After introducing the heat of aluminum molten metal reaction and the waste heat from the fuel cell stack exhaust gas, the equivalent heating power of the present invention is increased to 716.67 W. The fuel cell stack temperature rise process can be expressed by the following formula:

[0113] In the formula, The temperature of the fuel cell stack will be 40°C for the next control cycle. The current temperature of the fuel cell stack is 40°C during the current control cycle. To control the cycle length, For the first k The equivalent preheating power input to the fuel cell stack preheating process in each control cycle This is the equivalent heat capacity.

[0114] Under the above assumptions, the required temperature rise is 43 K, and the equivalent heat capacity is 18 kJ / K. Therefore, the start-up time of this invention is 18.00 min, as detailed in Table 6. Figure 9 .

[0115] Table 6

[0116] III. Stability Conditions of DC Bus (Power Conversion and Distribution Unit 42) In this simulation example, the rated DC bus voltage is 48 V, and the simulation time step is 1 s. The baseline scheme uses unbuffered energy storage or ordinary power follower control, with a maximum voltage deviation of ±4.80 V, a root mean square ripple of 2.05 V, and a peak load response time of 4.00 s. The scheme of this invention uses predictive control, auxiliary energy storage, and DC / DC coordinated control, with a maximum voltage deviation controlled within ±1.20 V, a root mean square ripple of 0.48 V, and a peak load response time of 1.20 s. The reduction ratio of the maximum voltage deviation is calculated by the following formula:

[0117] The reduction ratio of root mean square ripple is calculated using the following formula:

[0118] The comparison results are shown below. Figure 10As shown in Table 7, there is overlap between the baseline scheme (A) and the present invention scheme (B) before and after the load disturbance. This overlap indicates that both schemes maintain a voltage near the rated DC bus voltage of 48 V under steady-state conditions. Differences exist within the disturbance range: specifically, the maximum voltage deviation of the baseline scheme is ±4.80 V, while the maximum voltage deviation of the present invention scheme is reduced to ±1.20 V, a reduction of 75.0%; the root mean square fluctuation is reduced from 2.05 V to 0.48 V, a reduction of 76.6%; and the peak load response time is shortened from 4.00 s to 1.20 s, a shortening of 70.0%. These differences within the disturbance range characterize the suppression effects of different control schemes on the transient voltage deviation and fluctuation amplitude of the bus. This demonstrates that predictive control, auxiliary energy storage, and DC / DC coordinated control can suppress DC bus voltage fluctuations, improve peak load response speed, and enhance the output stability of the power conversion and distribution unit 42.

[0119] Table 7

[0120] IV. Water Reuse Operation In this simulation example, the water generated by the fuel cell stack 40 is estimated based on the stoichiometric relationship of the hydrogen-oxygen fuel cell reaction, that is:

[0121] The amount of water generated by the fuel cell stack 40 was calculated based on the hydrogen consumption during cruise operation. The theoretical water consumption for the aluminum slurry reaction is 1.620 kg; if further calculated based on the theoretical water consumption of the aluminum slurry reaction, the theoretical water consumption is 3.240 kg. In the baseline scheme, the water generated by the fuel cell stack 40 is directly discharged, with an external water replenishment of 3.240 kg; in this invention, 70% of the generated water is purified and returned to the aluminum slurry reactor 10, with a recycled water volume of 1.134 kg and an external water replenishment of 2.106 kg. The reduction in external water replenishment is calculated using the following formula: Compared to the baseline scheme that does not reuse generated water, the reduction in external water replenishment is as follows:

[0122] Therefore, 70% represents the reuse rate of water generated by the fuel cell stack, not the reduction rate of external water replenishment; the reduction rate of external water replenishment should be calculated based on the theoretical water consumption requirement of the aluminum-water reaction.

[0123] See results Figure 11 See Table 8.

[0124] Table 8

[0125] Depend on Figure 11 As shown in Table 8, in the baseline scheme, the water generated by the fuel cell stack 40 is not reused, and the external water replenishment is 3.240 kg. In the scheme of this invention, 70% of the water generated by the fuel cell stack 40 is purified and recycled, with a recycled water volume of 1.134 kg, reducing the external water replenishment to 2.106 kg, a reduction of 35.0% in external water replenishment requirements. This indicates that the product processing and water circulation subsystem 6 can convert the water generated by the fuel cell stack 40 into a source of replenishment water for the aluminum water reaction, reducing the external water replenishment requirement and improving the system's closed-loop material management capability.

[0126] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An aluminum-water battery-fuel cell hybrid power system for autonomous underwater vehicles, characterized in that, It includes a hydrogen production subsystem based on aluminum-water reaction, a hydrogen pressure regulation and supply unit, a seawater oxygenation and supply subsystem, a fuel cell power generation system, a waste heat recovery and thermal management subsystem, a product processing and water circulation subsystem, and an energy management and safety control subsystem. The aluminum-water reaction hydrogen production subsystem includes an aluminum-water reactor. The fuel inlet of the aluminum-water reactor is connected to an aluminum fuel tank, and the reactant outlet is sequentially connected to a gas-liquid separator, a hydrogen purifier, and a buffer hydrogen storage tank. The liquid outlet of the gas-liquid separator is sequentially connected to a circulating electrolyte tank, a circulating pump, and a filter. The filter is connected to the liquid inlet of the aluminum-water reactor. The hydrogen pressure regulating and supply unit is connected to a buffer hydrogen storage tank for regulating the pressure of the output hydrogen. The seawater oxygenation and supply subsystem includes a seawater oxygen supply branch and a secondary oxygen supply branch; The fuel cell power generation system includes a fuel cell stack. The anode of the fuel cell stack is connected to a hydrogen pressure regulation and supply unit, the cathode is connected to a seawater oxygenation and oxygen supply switching subsystem, and the output end is connected in sequence to a power conversion module, a power conversion and distribution unit, and an auxiliary energy storage unit. The waste heat recovery and thermal management subsystem is connected to the aluminum water reactor and the fuel cell stack, respectively, to recover and utilize the heat generated by the electrolyte and the exhaust gas of the fuel cell stack. The product processing and water circulation subsystem is connected to the aluminum water reactor and the fuel cell stack, respectively, and is used to recover the by-products generated by the aluminum water reactor and to purify and recover the wastewater generated by the fuel cell stack. The energy management and safety control subsystem is connected to the aluminum water reactor, hydrogen pressure regulation and supply unit, seawater oxygenation and supply subsystem, fuel cell stack, waste heat recovery and thermal management subsystem, and product processing and water circulation subsystem, respectively. The energy management and safety control subsystem includes: The multi-source state perception and data fusion unit is used to acquire the state parameters of the aircraft, environmental parameters, hydrogen pressure after pressure regulation, temperature of the aluminum water reactor, oxygen supply parameters of the seawater oxygenation and oxygen supply subsystem, power parameters of the fuel cell stack, and product collection status and historical power sequence of the product processing and water circulation subsystem. Load forecasting unit, used to determine forecasted power demand; The power gap determination unit is used to determine the actual output power of the fuel cell stack, the sustainable output power of the fuel cell stack, and the current maximum output power of the auxiliary energy storage unit; based on the actual output power of the fuel cell stack, the sustainable output power of the fuel cell stack, and the current maximum output power of the auxiliary energy storage unit, it determines the current available power; and based on the predicted power demand and the current available power, it determines the positive power gap. The mode decision unit is used to determine the mode of the aircraft based on the positive power gap, and issue control commands to the aluminum water reactor, hydrogen pressure regulation and supply unit, seawater oxygenation and oxygen supply subsystem, fuel cell stack, waste heat recovery and thermal management subsystem or product processing and water circulation subsystem.

2. The aluminum-water battery-fuel cell hybrid power system for autonomous underwater vehicles according to claim 1, characterized in that, The energy management and safety control subsystem also includes: The environmental and oxygen supply condition assessment unit is connected to the multi-source state sensing and data fusion unit. It is used to assess the oxygen supply capacity of the seawater oxygen supply branch based on the dissolved oxygen concentration, oxygen partial pressure, seawater flow rate, oxygen enrichment chamber status and cathode oxygen demand, and output the oxygen supply capacity assessment results to the model decision unit. The system health status diagnosis unit is connected to the multi-source status perception and data fusion unit. It is used to detect anomalies based on the vehicle's status parameters, environmental parameters, hydrogen pressure after pressure regulation, temperature of the aluminum water reactor, oxygen supply parameters of the seawater oxygenation and oxygen supply subsystem, power parameters of the fuel cell stack, leakage monitoring signals, and product collection status of the product processing and water circulation subsystem. When an abnormal data is detected, the vehicle's safety interlock unit is invoked.

3. The aluminum-water battery-fuel cell hybrid power system for autonomous underwater vehicles according to claim 1, characterized in that, Based on the positive power deficit, the vehicle's mode is determined, and corresponding control commands are issued to the aluminum water reactor, hydrogen pressure regulation and supply unit, seawater oxygenation and supply subsystem, fuel cell stack, waste heat recovery and thermal management subsystem, or product processing and water circulation subsystem, including: Based on the positive power gap, the hydrogen pressure after pressure regulation, the oxygen partial pressure, the dissolved oxygen concentration in seawater, the auxiliary energy storage SOC, the temperature of the fuel cell stack, the temperature of the aluminum water reactor, the product collection status, the liquid level of the liquid collection and distribution unit, and the liquid level of the product water collection unit, the mode of the aircraft is determined, and the corresponding outputs of hydrogen production intensity, oxygen supply mode, fuel cell stack power, auxiliary energy storage unit power, DC / DC output current, electrolyte circulation flow rate, spray duty cycle, input ratio of thermal management and waste heat distribution unit, or opening degree of drainage branch are determined.

4. The aluminum-water battery-fuel cell hybrid power system for autonomous underwater vehicles according to claim 1, characterized in that, The hydrogen pressure regulating and supply unit includes a first pressure reducing valve, a hydrogen pressure sensor, a buffer pressure regulating chamber, and a first solenoid valve connected in sequence. The inlet of the buffer pressure regulating chamber is connected to the gas outlet of the gas-liquid separator. The first pressure reducing valve is connected to the buffer hydrogen storage tank, and the first solenoid valve is connected to the anode of the fuel cell stack.

5. The aluminum-water battery-fuel cell hybrid power system for autonomous underwater vehicles according to claim 1, characterized in that, The seawater oxygenation and oxygen supply switching subsystem includes a biomimetic artificial gill module, and the outlet end of the biomimetic artificial gill module is connected in sequence to an oxygen enrichment chamber and a vacuum pump. The vacuum pump is connected to the fuel cell stack via an oxygen supply control valve, which is also connected to a secondary oxygen supply branch. The oxygen supply control valve is used to switch between the vacuum pump and the secondary oxygen supply branch.

6. The aluminum-water battery-fuel cell hybrid power system for autonomous underwater vehicles according to claim 1, characterized in that, The waste heat recovery and thermal management subsystem includes: The dual-plate closed-channel heat exchanger has a first inlet connected to a hydrogen pressure regulating and supply unit, forming a hydrogen preheating branch; a second inlet connected to a seawater oxygenation and oxygen supply switching subsystem, forming an oxidant preheating branch; and both the first and second outlets connected to a fuel cell power generation system. The thermal management and waste heat distribution unit has its inlet end connected to the circulating electrolyte tank and the exhaust gas outlet of the fuel cell stack, respectively, and its outlet end connected to the double-plate closed-circuit heat exchanger and the equipment compartment heat exchanger, respectively. The thermal management and waste heat distribution unit is also electrically connected to the energy management and safety control subsystem. It is used to input the circulating electrolyte into the equipment compartment heat exchanger and the exhaust gas of the fuel cell stack into the double-plate closed-circuit heat exchanger according to the instructions of the energy management and safety control subsystem in the cold start auxiliary preheating mode, and to adjust the input ratio.

7. The aluminum-water battery-fuel cell hybrid power system for autonomous underwater vehicles according to claim 1, characterized in that, The product handling and water circulation subsystem includes: The liquid collection and separation unit is connected to the aluminum water reactor at the inlet and to the aluminum hydroxide precipitator and Al(OH)3 collection chamber at the outlet in sequence. The water collection unit has an inlet connected to the fuel cell stack and an outlet connected in sequence to an ultrafiltration membrane treatment unit, a pure water buffer tank, and a water pump. The output end of the water pump is connected to the aluminum water reactor, the auxiliary cooling branch, and the discharge branch, respectively.

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